1. Field of the Invention
The invention relates to a navigation device performs guidance by using first map data containing first information and second map data containing second information which is not contained in the first map data, the coordinates of both of which overlap with each other.
2. Description of Related Art
A navigation device is widely used to display a host position or to guide a path to a destination by using road map information. The road map information used by the navigation device may contain different types of data such as data for searching a path and background data. Actual roads, landforms, or the like are frequently changed due to new construction and integration of roads, land development, or the like. That is, since actual roads or landforms do not match the road map information, preferably, the road map information used by the navigation device is properly updated. As described above, the road map data may contain different types of data, and in many cases, update timings of data are different from each other. As a result, an inconsistency among the different types of data may occur, for example, a mismatch between guidance paths and roads displayed on a display device may occur such that a user cannot comprehend the content displayed.
Japanese Unexamined Patent Application Publication No. 2005-265574 (JP 2005-265574A) discloses a navigation device that tones down and displays an inconsistent portion in a case where there is an inconsistency between data for searching a path and background data (map display data). In a case where there is an inconsistency in an updated state, it is possible to visually notify a user of the occurrence of inconsistency of data by displaying an inconsistent portion in a different manner. Accordingly, even if incomprehensible display appears, the user can continuously drive a vehicle without becoming confused (refer to 45 to 47 paragraphs, FIG. 5, and the like in JP 2005-265574A).
Technology disclosed in JP 2005-265574A is capable of clearly notifying a user of the occurrence of inconsistency of data without confusing the user. In contrast, it is not possible to reduce the occurrence of phenomena caused by the inconsistency of data, for example, the occurrence of such a phenomenon that a map is not partially displayed. For example, even if inconsistency of data occurs, road map information is preferably displayed matching as closely to actual roads or landforms as possible, and a phenomenon caused by the inconsistency of data is preferably eliminated as much as possible.